Weight loss is a multi-factorial process that is not fully understood. That being said, science concludes 7 major factors affect weight loss:
7- Environment
Obviously, you cannot do much about genetics; that boat sailed long ago; blame your parents. The rest of these items are on the table. As I am sure you know, all of these factors are interrelated, some more than others. I want to focus on diet, exercise and activities of daily living because they are the major factors in energy conversion. A goal of weight loss is to use more energy than you take in. Balancing bodily energy is a lot more complicated than calories in (the food we eat) and calories out (exercise and activities of daily living). Calories eaten and subsequently used during voluntary movements are only two small parts of the energy equation and insignificant by themselves. Your total energy expenditure fluctuates daily and is quite difficult to measure accurately. Most of your calories are spent on metabolic processes:
calories are burned during all involuntary movements (breathing, heartbeat, etc.)
heating the body due to environmental temperatures
calories are used in bone and soft-tissue growth
the largest caloric drain on the body comes from brain functions
metabolism of food
calories used on an everyday basis to combat infections
tissue restoration
Everyone burns calories at a different rate. Furthermore, many people are better adapted for certain exercises/movements and burn less energy when performing those tasks. If Micheal Moore challenged Lance Armstrong to a bike race, not only would Mr. Moore lose the race, he’d probably burn a lot more calories too. Mr. Armstrong’s body has specifically adapted to biking. It has become extremely efficient in that movement pattern (and his VO2 max, resting heart rate, recovery heart rate, lactic acid threshold, body weight, muscle mass, etc. are all much better than Moore’s – this is just a guess) thus using less energy.
There is no one best form of aerobic exercise or machine that burns the most calories. According to Kravitz and Robergs, “based on the fundamental principles of indirect calorimetry, to burn more calories during exercise, you need to increase oxygen consumption. The issue of exercise and caloric expenditure is as simple as that.” Research shows the greatest impact on caloric expenditure during exercise comes from the contraction of skeletal muscles, which therefore increases oxygen uptake. The more oxygen you need during exercise, the more calories you burn. Listed below are the other factors during exercise that play a role in calorie burn:
the number of muscle fibers being used
the complexity of the movement
prior experience with the exercise
weight-bearing exercise vs. non-weight bearing
balance and proprioception requirements
resistance and incline of the machine
your total body weight (the heavier you are, the more calories you burn)
the amount of lean muscle mass you have
speed and intensity level
duration of the exercise
the temperature of the room (colder rooms will induce higher energy demands)
Please keep in mind that any one of the machines listed below is capable of inducing a higher caloric expenditure than the other. This list is an estimation of which cardio machines have the potential of burning the most amount of calories when all other factors are equal:
Cross Country Skiing
Running on the treadmill
Rowing
Step-Mill (the one with real steps)
Elliptical with Arms Jump Rope
Biking upright
Recumbent biking
Arm ergometer
Most people benefit from switching aerobic machines once every 8 weeks. This is the approximate time it takes to adapt to a new movement skill. As your body becomes more familiar with the specific exercise, you burn fewer calories due to neuromuscular efficiencies. Another reason to switch every two months (or more) is to prevent linear wear patterns from developing within your joints. This is especially true in regards to fixed foot position machines like the elliptical or bike. Perhaps try something new like hiking, jump roping, kickboxing, trail running, swimming, etc. Depending on your goals, it may be a good idea to alter the speed, incline, and resistance of the exercise you choose.
Sources:
1. McARDLE, W.D. et al. (2000) Energy expenditure at rest and during physical activity. In: McARDLE, W.D. et al., 2nd ed. Essentials of Exercise Physiology, USA: Lippincott Williams and Wilkins. 2. DAVIS, B. et al. (2000) Physical Education and the Study of Sport. UK: Harcourt Publishers Ltd. 3. MayoClinic.com; Exercise for Weight Loss; 2009 4. Borg G.A.V. Psycholphysical bases of perceived exertion. Med. Sci. Sports Exerc. 14:377-381, 1982.
5. Toner, M.M., Glickman, E.L., & McArdle, W.D. Cardiovascular adjustments to exercise distributed between the upper and lower body. Med. Sci. Sports. Exerc. 22:773-778, 1990.
Doug Joachim – NYC www.JoachimsTraining.com
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